Winter Stresses on Trees and Shrubs
Heavy snow and ice, as well as frozen soil conditions, can damage cherished trees and shrubs in residential landscapes. Even areas without major snowfall experience high winds and huge fluctuations in temperatures during winter. But homeowners can lessen the adverse effects of winter weather with preventive maintenance.
What can happen in winter, and how can you avoid it?
"Branches of trees can break due to the excessive weight of ice or snow," says Tchukki Andersen, BCMA, CTSP and staff arborist with the Tree Care Industry Association (TCIA). "Proper pruning encourages the formation of the strongest possible branches and branch attachments. When pruning alone isn't enough, properly installed cables and rigid braces can add support to a weakened part of the tree."
Winter winds cause evergreens to lose moisture from their needles. Even some deciduous trees suffer from winter drying. If water is not available as moisture is drawn from living cells, permanent damage will result. The best prevention consists of planting only hardy species in areas of prolonged exposure, watering plants adequately in the fall, and mulching to insulate the soil and roots from severe cold.
On sunny days in winter, the tree's trunk and main limbs can warm to 15 degrees higher than the air temperature. As soon as the sun's rays stop reaching the stem when the sun sets, the tree's temperature plummets, causing injury or permanent damage to the bark. The two common types of injury are sun scald and frost cracking. The effects of sun scald and frost cracking can be reduced by sound arboricultural practices to maintain overall health, and by covering the trunks of young, susceptible trees with a suitable tree wrap.
Winter is a good time to prune
"Most skilled arborists prefer pruning when trees are dormant," says Andersen. "With no leaves on the tree, the arborist is better able to evaluate its architecture and spot dead or diseased branches. In addition, since the ground is frozen, damage to the turf underneath the tree due to falling limbs and tree care activities is negligible. This is also a good time to check trees for diseases and other damage."
Here are some other things TCIA recommends to improve the health of your living landscape: